WO2009050031A1 - Use of a polyamide molding compound for lining conduits - Google Patents

Abstract

In a method for introducing an inliner into a pipe or a conduit, wherein the outer diameter of the inliner is larger than the inner diameter of the pipe or conduit, and wherein the cross-section of the inliner is reduced by the effect of an outside force before the introduction, the inliner comprises a polyamide molding compound containing at least 50 wt.-% polyamide, which is not PA11. The reset behavior of said polyamides is similar to the polyethylene commonly used for this purpose.

Description

 Use of a polyamide molding compound for lining pipes

The invention relates to the use of an inliner of a specified polyamide molding compound for pipes, pipelines or ducts, the pipelines or ducts for the transport of district heating, fresh water, sewage, oil, gas or similar media.

District heating, fresh water, sewage, oil or gas pipelines or other media transporting lines or ducts have a limited service life. Leads laid long ago are therefore often defective, so that z. B. wastewater escape into the surrounding groundwater or pending groundwater can enter the sewer pipes. The reason for this is on the one hand the progressive corrosion damages, on the other hand the increasing mechanical load, as they occur by traffic vibrations, pressure load or Erdbewegungen in the context of civil engineering measures or in mining areas. The candidate lines or channels are about 1 m deep or more in the ground, so that a replacement of the lines or channels over the entire length would be possible only with considerable effort. There is therefore a need for remediation methods with which defective lines of the supply and disposal network can be rehabilitated cost.

In addition, the lines in question are often also equipped ex works with an inliner. This serves u. a. Prevention of corrosion damage. So z. B. pipes for the transport of crude oil already ex works with an inliner and then z. B. on the seabed, in the ground or installed above ground.

The prior art polyethylene liners have a number of disadvantages. For example, their swelling and diffusion behavior is poor, especially if organic liquids, such as crude oil, petrochemicals or wastewater containing organic liquids such. As solvents, contains promoted. The diffusion behavior is also disadvantageous in gas lines. Polyethylene is also susceptible to stress cracking, eg. B. on contact with surfactants and notch sensitive. Due to the low softening point and the lack of media resistance of polyethylene, liners made of this material can only be used up to operating temperatures of a maximum of 65 ^° C.

For some time, polyamide 11 (PA11) inliners have been used offshore in steel pipes used to extract crude oil or crude gas (J. Mason, OiI & Gas Journal, Oct. 18, 1999, pp. 76-82). The outer diameter of the Rohrinliners is designed slightly larger than that of the pipe to be lined. In order to introduce the inliner, this is then reduced in its cross section by stretching, upsetting or folding. After the introduction of the inliner puts this by resetting to the pipe inner wall. This process can be supported by pressure and temperature. The tube thus lined has no annulus. As an example of a method known to the person skilled in the art, the Swagelining ™ and the roll-down can be mentioned. The inliner can be introduced in this way already factory. Inliners made of polyethylene are now introduced by default by these methods in pipes.

German patent application no. 10 2006 038 108.4 discloses an inliner for a pipeline which consists of a polyamide molding compound.

Due to the restoring behavior of the currently available PA11 molding compounds, the introduction of the corresponding inliners can only be implemented to a limited extent, in particular by means of the roll-down method. This is due to the fact that the diameter compressed PA11 liners due to the very fast recovery behavior of the PA11 - molding compounds when inserted into the tube too quickly to the pipe inner wall of the pipe to be lined and thus complicates a complete retraction of the inliner or prevented. This can be stopped by inserting the corresponding inliners only in very short pipe sections. However, this is considered uneconomical, since the use of short pieces of pipe leads to an increased number of joints. The resulting costs and additional potential defects are not acceptable.

Another way around these difficulties is that the inliner is dimensioned so that it no or only a minimal contact pressure Having provision to the pipe inner wall of the main pipe. (Y. Giacomelli & B. Howard, 4th MERL Oilfield Engineering with Polymers Conference 2003, Qualification of Plastic Lined Pipelines For Hydrocarbon Transport). In extreme cases, the design even provides for a minimal annular gap. However, this means that the liner is not ideally fixed in the pipe and later problems such as faults can occur.

The object of the present invention was to avoid these disadvantages and to provide a polyamide molding composition for the manufacture of a liner for pipelines, which on the one hand has the good properties of the commonly used materials based on polyamide and on the other hand also by reducing the Cross-section can be introduced by stretching, upsetting or folding in a tube without the difficulties described above occur.

Surprisingly, it has been found that polyamide molding compositions based on a polyamide, which is not PA11, differ so strongly in their restoring behavior from PA11-based molding compositions that they can be provided for use as inliners described above.

The invention accordingly provides a method for introducing an inliner into a pipe or a pipeline, wherein the outer diameter of the inliner is slightly larger than the inner diameter of the pipe, and wherein the cross section of the inliner by the application of an external force before insertion wherein the inliner consists of a polyamide molding composition which contains at least 50% by weight, at least 60% by weight, at least 70% by weight or at least 80% by weight of polyamide which is not PA11.

In the narrower sense, "pipe" here means a transportable section, and a plurality of such pipes are joined together to form a pipeline. Due to the excess of the liner in relation to the pipe or the pipe, the reverse deformation of the inliner after the infeed guarantees a permanent close-fit position.

The difference of the claimed diameter is at least an infinitesimal small amount. Typically, the outer diameter of the liner is at most 10% and preferably at most 6% greater than the inner diameter of the pipe or the pipe.

Suitable methods for introducing an inliner with an oversize into a pipe or a pipeline are described, for example, in the following patent applications: EP-A-0 562 706, EP-A-0 619 451, WO 95/27168, WO 98/02293, WO 01/16520, EP-A AO 377 486, EP-AO 450 975, EP-AO 514 142 and WO 96/37725.

During stretching, upsetting or folding, the cross section of the inliner is generally reduced by at least 3%, preferably by at least 4%, more preferably by at least 5%, more preferably by at least 6% and most preferably by at least 7%.

A suitable introduction method is, for example, Swagelining ™. After inline tubes have been butt-welded to a section which is slightly longer than the section of the support tube to be rehabilitated, this is pulled through a die, which temporarily reduces the tube diameter. As a result, the inliner can be drawn into the smaller tube interior of the carrier tube. After the inliner has been completely retracted into the support tube, the tensile force is relieved. As a result, the inliner endeavors to return to its original diameter until it bears firmly against the inner wall of the carrier tube. Due to the tight-fitting inliner, the flow capacity of the rehabilitated pipeline comes very close to the original one.

Another suitable method is the introduction Roll Down ^® process. Here, too, inliner pipes are first joined in situ by butt welding. To allow a feeder, the cross-section of the inliner in the roll-down machine with Help reduced paired roles. The rate of deformation is typically one to three meters per minute. After insertion, the pipe ends can be closed and the inliner pressurized with water pressure. As a result, the return to its original diameter can be additionally supported and the inliner lays close to the pipe inner wall. Compared with swagelining, lower pull forces are required when pulling in the inliner, which leads to lower material load and higher speeds of entry.

The folding is described, for example, in EP-A-0 377 486.

Suitable polyamides are all except PA11 and copolyamides which contain at least 40% by weight of units derived from co-aminoundecanoic acid. In the context of the invention, in particular those polyamides which are derived from one or more of the following monomers are suitable:

a) a lactam or the corresponding co-aminocarboxylic acid having 6, 7, 8, 9, 10 or 12 C atoms and b) a substantially equimolar mixture of a diamine having 4 to 22 C atoms and a dicarboxylic acid having 6 to 22 C-atoms.

Examples of suitable diamines are tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, octamethylenediamine, nonamethylenediamine, 2-methyl-1,5-diaminopentane, 2,2,4- and 2,4,4-thmethylhexamethylenediamine, decamethylenediamine, dodecamethylenediamine, 4,4'-diaminodicyclohexylmethane, 3,3'-dimethyl-4,4 ' diaminodicyclohexylmethane, 4,4'-diaminodicyclohexylpropane, 1,4-diaminocyclohexane, 1,4-bis (aminomethyl) cyclohexane, 2,6-bis (aminomethyl) norbornane, 3-aminomethyl-3,5,5-trimethylcyclohexylamine, 1,13-diaminotridecane, 1,14-diaminotetradecane, 1,16-diaminohexadecane and 18.1-diaminooctadecane. It is also possible to use mixtures of different diamines.

Suitable dicarboxylic acids are, for example, adipic acid, 2,2,4- or 2,4,4-trimethyladipic acid, azelaic acid, suberic acid, 1,9-nonanedioic acid, 1,10-decanedioic acid, 1.11-undecanedioic acid, 1.12-dodecanedioic acid, 1.13-tridecanedioic acid, 1.14-tetradecanedioic acid, 1.16-hexadecanedioic acid, 1.18-octadecanedioic acid, cyclohexane-1,4-dicarboxylic acid, 4,4'-dicarboxydicyclohexylmethane, 1,4-bis (carboxymethyl) cyclohexane, terephthalic acid, isophthalic acid and naphthalene-2,6 dicarboxylic acid. It is also possible to use mixtures of different dicarboxylic acids.

In addition, the polyamide may contain branching building blocks, which are derived for example from tricarboxylic acids, triamines or polyethyleneimine.

The polyamide may also be a polyetheresteramide or a polyetheramide. Polyetheresteramides are z. B. from DE-A-25 23 991 and DE-A-27 12 987 known; they contain as comonomer a polyether diol. Polyetheramides are known, for example, from DE-A-30 06 961; they contain as comonomer a polyether diamine.

In the case of the polyether diol or the polyether diamine, the polyether unit may be based, for example, on 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol or 1,3-butanediol. The polyether unit can also be of mixed construction, for example with random or blockwise distribution of the units derived from the diols. The weight average molecular weight of the polyether diols or polyether diamines is from 200 to 5000 g / mol and preferably from 400 to 3000 g / mol; their proportion of the polyetheresteramide or polyetheramide is preferably 4 to 60 wt .-% and particularly preferably 10 to 50 wt .-%. Suitable polyether-diamines are obtainable by conversion of the corresponding polyether-diols by reductive amination or coupling to acrylonitrile with subsequent hydrogenation; they are z. B. ^® in the form of JEFFAMINE D grades of Huntsman Corp. or in the form of the polyetheramine D series commercially available from BASF SE.

Polyamides which are suitable in the context of the invention are, for example, PA6, PA66, PA610, PA612, PA613, PA88, PA810, PA812, PA1010, PA1012, PA1014, PA12, PA1212 and polyetheresteramides and polyetheramides based thereon. Likewise, mixtures of different polyamides, provided sufficient compatibility can be used. Compatible polyamide combinations are known to the person skilled in the art; For example, the combination PA12 / PA1012, PA12 / PA1212, PA612 / PA12, PA613 / PA12, PA1014 / PA12 and PA610 / PA12 are listed here. In case of doubt, compatible combinations can be determined by routine tests.

In a preferred embodiment of the invention, a mixture of 30 to 99 wt .-%, preferably 40 to 98 wt .-% and particularly preferably 50 to 96 wt .-% polyamide in the strict sense and 1 to 70 wt .-%, is preferred 2 to 60 wt .-% and particularly preferably 4 to 50 wt .-% polyetheresteramide and / or polyetheramide used. The use of polyetheramides is preferred because of the better hydrolytic stability.

Due to the presence of the polyetheresteramide or polyetheramide, the

Polyamide molding compound softened and is thus better deformable without the restoring behavior suffers. Compared with the use of low molecular weight plasticizers, the non-extractability of the polymeric plasticizer is advantageous here, since the shrinkage risk of the liner during operation is eliminated, which can lead to the liner losing the wall friction to the carrier tube.

The polyamide molding composition may contain the usual additives. Illustrative examples thereof are colorants, flame retardants and protectants, stabilizers, fillers, lubricity improvers, mold release agents, impact modifiers, plasticizers, crystallization accelerators, antistatic agents, lubricants, processing aids, and other polymers commonly compounded with polyamides.

Examples of these additives are as follows: colorants: titanium dioxide, lead white, zinc white, lithopone, antimony white, carbon black,

Iron oxide black, manganese black, cobalt black, antimony black, lead chromate, red lead, zinc yellow, zinc green, cadmium red, cobalt blue, berlin blue, ultramarine, manganese violet, cadmium yellow, penta green, molybdenum orange and red, Chrome orange and red, iron oxide red, chromium oxide green, strontium yellow, molybdenum blue, chalk, ocher, umber, green earth, Terra di Siena calcined, graphite or soluble organic dyes.

Flame retardants and flame retardants: antimony trioxide, hexabromocyclododecane, tetrachloro- or tetrabromobisphenol and halogenated phosphates, borates, chloroparaffins and red phosphorus, furthermore stannates, melamine cyanurate and its condensation products such as melam, Meiern, melon, melamine compounds such as melamine pyrophosphate and polyphosphate, ammonium polyphosphate, aluminum hydroxide, calcium hydroxide and organophosphorus compounds which do not contain halogens, such as resorcinol diphenyl phosphate or phosphonic acid esters.

Stabilizers: metal salts, in particular copper salts and molybdenum salts and copper complexes, phosphites, hindered phenols, secondary amines, UV absorbers and HALS stabilizers.

Fillers: glass fibers, glass beads, ground glass fiber, diatomaceous earth, talc, kaolin, clays, CaF ₂ , aluminum oxides and carbon fibers.

Lubricity improvers and lubricants: MoS ₂ , paraffins, fatty alcohols, fatty acid amides and stearates of divalent or trivalent metals.

Mold release agents and processing aids: waxes (montanates), montanic acid waxes, montan ester waxes, polysiloxanes, polyvinyl alcohol, SiO ₂ , calcium silicates and perfluoropolyethers.

Impact modifiers: polybutadiene, EPM, EPDM, HDPE, acrylate rubber.

Antistatic agents: carbon black, carbon fibers, graphite fibrils, polyhydric alcohols, fatty acid esters, amines, acid amides, quaternary ammonium salts.

Other polymers: ABS, polypropylene. These additives can be used in the usual amounts known to those skilled in the art.

In a preferred embodiment, the polyamide molding composition contains from 1 to 25% by weight of plasticizer, more preferably from 2 to 18% by weight, and especially preferably from 3 to 15% by weight.

Plasticizers and their use in polyamides are known. A general overview of plasticizers which are suitable for polyamides can be found in Gächter / Müller, Kunststoffadditive, C. Hanser Verlag, 2nd Edition, page 296.

As plasticizers suitable, conventional compounds are, for. B. esters of p-hydroxybenzoic acid having 2 to 20 carbon atoms in the alcohol component or amides of arylsulfonic acids having 2 to 12 carbon atoms in the amine component, preferably amides of benzenesulfonic acid.

As plasticizers come u. a. Ethyl p-hydroxybenzoate, octyl p-hydroxybenzoate, i-hexadecyl p-hydroxybenzoate, n-octyl toluene sulfonamide, benzenesulfonic acid n-butylamide or benzenesulfonic acid 2-ethylhexylamide are suitable.

The inliner is preferably produced by means of a process in which the polyamide of the molding composition has been condensed by adding a compound having at least two carbonate units in a proportion of 0.005 to 10 wt .-%, based on the polyamide, wherein

a) a starting polyamide molding composition was provided, b) a premix of the starting polyamide molding compound and the compound having at least two carbonate units was prepared c) the premix was optionally stored and / or transported and d) the premix was then processed into a molding, wherein only in this step, the condensation took place. Surprisingly, it has been found that in this mode of addition, a significant increase in melt stiffness occurs during processing, with a simultaneously low engine load. Thus, despite high melt viscosity high throughputs can be achieved during processing, resulting in an improvement in the economics of the manufacturing process.

Preferably, the starting polyamides used here have molecular weights M _n of greater than 5000, in particular greater than 8000. Here, polyamides are used whose end groups are at least partially present as amino groups. For example, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80% or at least 90% of the end groups are present as amino end groups. The preparation of polyamides having a higher amino terminal content using diamines or polyamines as regulators is state of the art. In the present case, an aliphatic, cycloaliphatic or araliphatic diamine having from 4 to 44 carbon atoms is preferably used as regulator in the preparation of the polyamide. Suitable diamines are, for example, hexamethylenediamine, decamethylenediamine, 2,2,4- or 2,4,4-trimethylhexamethylenediamine, dodecamethylenediamine, 1,4-diaminocyclohexane, 1,4- or 1,3-dimethylaminocyclohexane, 4,4'-diaminodicyclohexylmethane, 4,4'-diamino-3,3'-dimethyldicyclohexylmethane, 4.4 ' Diaminodicyclohexylpropane, isophoronediamine, metaxylylenediamine or paraxylylenediamine.

In a further preferred embodiment, a polyamine is used as regulator and simultaneously branching agent in the preparation of the polyamide. Examples of these are diethylenethamine, 1,5-diamino-3- (β-aminoethyl) pentane, ths (2-aminoethyl) amine, N ₁ N-bis (2-aminoethyl) -N ', N'bis [2- [bis (2 -aminoethyl) amino] -ethyl] -1, 2-ethanediamine, dendrimers and polyethyleneimines, in particular branched polyethyleneimines which are obtainable by polymerization of aziridines (Houben-Weyl, Methods of Organic Chemistry, Volume E20, pages 1482 to 1487, Georg Thieme Verlag Stuttgart, 1987) and generally have the following amino group distribution:

25 to 46% primary amino groups,

30 to 45% secondary amino groups and 16 to 40% tertiary amino groups.

In the process according to the invention, at least one compound having at least two carbonate units in an amount ratio of 0.005 to 10% by weight, calculated in relation to the polyamide used, is used. Preferably, this ratio is in the range of 0.01 to 5.0 wt .-%, particularly preferably in the range of 0.05 to 3 wt .-%. The term "carbonate" here means esters of carbonic acid, in particular with phenols or alcohols.

The compound having at least two carbonate units may be low molecular weight, oligomeric or polymeric. It may consist entirely of carbonate units or it may have other units. These are preferably oligo- or polyamide, ester, ether, ether ester amide or ether amide units. Such compounds can be prepared by known oligo- or polymerization processes or by polymer analogous reactions.

In a preferred embodiment, the compound having at least two carbonate units is a polycarbonate, for example based on bisphenol A, or a block copolymer containing such a polycarbonate block.

The metered addition of the compound used as additive with at least two carbonate units in the form of a masterbatch allows a more accurate metering of the additive, since larger amounts are used. It also turned out that the use of a masterbatch improves the quality of the extrudate. The masterbatch comprises as matrix material preferably the polyamide, which is also condensed in the process according to the invention, or a polyamide compatible therewith, but also incompatible polyamides can undergo a partial binding to the polyamide to be condensed under the reaction conditions, which causes compatibilization. The polyamide used as the matrix material in the masterbatch preferably has a molecular weight M _n greater than 5,000 and in particular greater than 8,000. In this case, those polyamides may be used whose end groups are present predominantly as carboxylic acid groups. For example, at least 80%, at least 90% or at least 95% of the end groups are acid groups.

The concentration of the compound having at least two carbonate units in the masterbatch is preferably 0.15 to 50 wt .-%, particularly preferably 0.2 to 25 wt .-% and particularly preferably 0.3 to 15 wt .-%. The preparation of such a masterbatch is carried out in the usual manner known to those skilled in the art.

Suitable compounds having at least two carbonate units and suitable masterbatches are described in detail in WO 00/66650, to which reference is expressly made.

An additive based on this principle for adjusting the molecular weight of polyamides is marketed by Brüggemann KG under the name Brüggolen M1251. Primary applications are in the field of viscosity adjustment for recyclate from PA6 or PA66, which is recycled in extrusion molding compounds. The additive Brüggolen M1251 is a masterbatch of a low-viscosity polycarbonate, for example Lexan 141, in an acid-terminated PA6. For the molecular weight build-up, a reaction of the amino end groups contained in the material to be condensed with the polycarbonate is the cause.

The effectiveness of the method is shown in WO 00/66650 using the example of the condensation of PA6 and PA66, wherein the corresponding polycondensates are partly used in pure form, but sometimes also contain additives.

The invention is applicable to polyamides which contain at least 5 ppm of phosphorus in the form of an acidic compound due to their production. In this case, the polyamide molding compound prior to compounding or compounding 0.001 to 10 wt .-%, based on the polyamide, of a salt of a weak acid added. Suitable salts are disclosed in DE-A 103 37 707, to which reference is hereby expressly made. However, the invention is equally applicable to polyamides which contain less than 5 ppm of phosphorus or no phosphorus in the form of an acidic compound as a result of the preparation. In this case, although not a corresponding salt of a weak acid must be added.

The compound having at least two carbonate units is added as such or as a masterbatch according to the invention only after compounding, but at the latest during processing. In the processing, the polyamide to be condensed or the polyamide molding compound to be condensed are preferably mixed as granules with the granules of the compound having at least two carbonate units or the corresponding masterbatch. However, it is also possible to prepare a granulate mixture of the ready-compounded polyamide molding compound with the compound having at least two carbonate units or the masterbatch, then transport or store it and then process it. Accordingly, of course, can be moved with powder mixtures. It is crucial that the mixture is only melted during processing. Thorough mixing of the melt during processing is recommended. The masterbatch can just as well be metered into the melt of the polyamide molding compound to be processed as a melt stream with the aid of a supplied extruder and then thoroughly mixed.

The process for producing the inliner is described in general terms in EP 1 690 889 A1 and EP 1 690 890 A1.

The wall of the inliner can either be single-layered and in this case consist entirely of the polyamide molding compound, but it can also be multi-layered, wherein the polyamide molding compound can form the outer layer, the inner layer and / or the middle layer. The other layer or layers consist of molding compositions based on other polymers, for example polyethylene, polypropylene or fluoropolymers. Such multi-layer structures can be produced according to the prior art inter alia by coextrusion.

In a preferred embodiment, the inliner is equipped with an anti-electrostatic finish so that static charge generated by friction with the transported medium can be dissipated. In the simplest case, it is an electrically conductive strip of metal or of a conductive molding compound, which is arranged either axially or spirally. It is better to provide a plurality of such strips at a preferably regular distance from one another, for example two, three, four, five, six, seven, eight, nine, ten, eleven or twelve. Alternatively, a layer of the inliner, preferably the innermost layer, consists of an electrically conductive molding compound. The conductivity is produced by adding metal fibers, carbon fibers, metallized carbon fibers, graphite fibers, and preferably conductive carbon black and / or graphite fibrils. Preferably, this is also a polyamide molding composition containing at least 50% polyamide, which is not PA11.

The pipeline in question may be a transport line, a distribution line or a service line and be designed either as a pressure line or as a gravity pipe. It serves, for example, the transport of district heating, fresh water, waste water, gas, oils such as crude oil, light oil or heavy oil, fuels such as kerosene or diesel, petrochemicals, brines, alkalis, abrasive media or dusts and can be, for example, a supply or disposal line. It is preferably laid in the ground, in tunnels or tunnels or in the water, but possibly also above ground.

In the context of the invention, the pipe can already be factory-equipped or when laying with the inliner to extend the service life during operation. In most cases, however, the inliner is subsequently introduced into the pipeline to rehabilitate it; This is called relining.

The candidate pipelines generally have an inner diameter of up to 2,000 mm, preferably up to 1,000 mm and more preferably up to 500 mm.

The invention also relates to a pipeline containing such an inliner.

With the help of the invention, a very durable renovation or sealing of a pipeline can be achieved. In the following, the method according to the invention will be explained by way of example. The following materials were used in the experiments:

Amine-regulated PA12 with 50 meq / kg NH ₂ groups and 9 meq / kg COOH groups, η _re ι about 2.15. Acid-regulated PA12 with 8 meq / kg NH ₂ groups and 50 meq / kg COOH groups, η _re ι about 2.15.

Brüggolen ^® M1251, a blend of a low-viscosity polycarbonate and an acid-terminated PA6.

Ceasit ^® PC calcium. PA12 VESTAMID ^® 2140, a commercially available PA12 extrusion grade of the applicant.

PA1010 a prepared from 1, 10-decanediamine and sebacic acid in a known manner Homopolyamid with a relative

Solution viscosity η _re ι _, determined in accordance with DIN EN ISO 307, of

2.1.

HDPE is a commercial tube extrusion type.

PA11 a commercially available type of the company. Arkema (RILSAN ^® BESNO).

First, the following blends were prepared in the melt, extruded and granulated:

Gemäß folgender Rezeptur wurde ein als „PA12/Brüggolen" bezeichneter hochmolekularer PA12-Typ auf einem 50er Reifenhäuser Einschneckenextruder mit Dreizonenschnecke (L = 25 D) hergestellt, extrudiert und granuliert:

According to the following formulation, a high molecular weight PA12 type called "PA12 / Brüggolen" was prepared on a 50 mm Reifenhäuser single screw extruder with three-zone screw (L = 25 D), extruded and granulated:

From the polyamides, compounds were prepared according to Table 1:

Table 1: Preparation of the compounds

The recovery behavior was determined by means of a compression test with subsequent recording of the recovery behavior of the corresponding molding compositions. The test specimens were prepared from injection molded plates measuring 110 x 150 x 6 mm using a milling cutter. On the test specimens of dimensions 10 × 10 × 6 mm thus obtained, a compression test was then carried out with a subsequent measurement of the residual value over a period of 24 hours. The specimens were first compressed by 20, 25 and 30% of the original sample thickness. After reaching the final compression, the force was reduced to zero and the reset path recorded continuously over 250 seconds. Subsequently, the sample thickness was measured again after 1 hour and after 24 hours.

Table 2: Test results at 20% compression

Table 3: Test results at 25% compression

Table 4: Test results at 30% compression

The comparison of the results shows that the tested polyamide molding compounds based on PA12 and PA1010 have a much slower recovery behavior than a comparable PA11 molding compound. It even turned out that that Resilience very similar to that of polyethylene. Analogous results were obtained with PA1212, PA613, PA1014, PA610, PA1012 and PA612.

Claims

claims: 1. A method for introducing an inliner in a pipe or a pipeline, wherein the outer diameter of the inliner is greater than the inner diameter of the pipe or the pipe, and wherein the cross section of the inliner Is reduced by the application of an external force before insertion, characterized in that the inliner consists of a polyamide molding composition containing at least 50 wt .-% polyamide, which is not PA11. 2. The method according to claim 1, characterized in that the cross section of the inliner is reduced by at least 3%. 3. The method according to any one of the preceding claims, characterized in that the polyamide of the polyamide molding composition to 1 to 70 wt .-% of polyetheresteramide and / or polyetheramide. 4. The method according to any one of the preceding claims, characterized in that the polyamide is selected from the group PA6, PA66, PA610, PA612, PA613, PA88, PA810, PA812, PA1010, PA1012, PA1014, PA12, PA1212 and based thereon polyetheresteramides and polyether amides. 5. The method according to any one of the preceding claims, characterized in that the polyamide molding composition contains 1 to 25 wt .-% plasticizer. 6. The method according to any one of the preceding claims, characterized in that the inliner was prepared by means of a method in which the polyamide of the molding composition by adding a compound having at least two Carbonate units in a ratio of 0.005 to 10 wt .-%, based on the polyamide, was condensed, wherein a) a starting polyamide molding composition was provided, b) a mixture of the starting polyamide molding compound and the compound having at least two carbonate units was prepared c) the premix was optionally stored and / or transported and d) the premix was then processed into a molding, wherein only in this step, the condensation took place. 7. Pipe containing a introduced according to claims 1 to 6 inliner. 8. Pipe according to claim 7, characterized in that it is the transport of district heating, fresh water, sewage, gas, oils, Fuels, petrochemicals, brines, alkalis, abrasive media or dusts.